1. Field of the Invention
This invention relates to a high performance multifilament yarn useful in industrial applications including the reinforcement of tires and the process for its production. 2. Description of the Prior Art
Polyethylene terephthalate filaments of high strength are well known in the art and are commonly utilized in industrial applications including tire cord for rubber reinforcement, conveyor belts, seat belts, V-belts and hosing.
Work has been done to establish that filamentary material which undergoes a relatively low degree of shrinkage for a high strength fibrous material and which exhibits a low degree of hysteresis or work loss is particularly suited for use in environments where elevated temperatures (e.g. 80.degree. to 180.degree. C.) are encountered and wherein the fibrous material is repeatedly fatigued. Davis et al. U.S. Pat. No. 4,101,525 provides a high strength multifilament polyester yarn with low shrinkage and work loss characteristics. Saito et al. U.S. Pat. No. 4,491,657 discloses high modulus, low shrinkage polyester yarn, but requires a low terminal modulus to achieve good yarn to treated cord conversion efficiency for such dimensionally stable yarns.
Continued improvement in high strength industrial yarns particularly suited for use as fibrous reinforcement in rubber tires is an ongoing need in the industry.